When it comes to wielding Congress's formidable investigatory power, it is hard to think of anyone in modern history who has done it as effectively as former representative Henry Waxman, D-Calif.
In the mid-1990s, he took on Big Tobacco with high-profile hearings, remembered for the moment when industry executives swore under oath that their product was not addictive. His exposure of that blatant lie helped pave the way for a landmark $246 billion legal settlement.
Waxman's other headline-grabbing probes included those digging into the use of performance-enhancing drugs in professional sports, the 2008 collapse of Wall Street, the waste and fraud in government spending in Iraq and the flawed intelligence that got this country into that war in the first place.
In various media profiles, the soft-spoken, 5-foot-5 congressman was dubbed "the Democrats' Eliot Ness," "the Bush administration's worst nightmare" and as the headline writers for a Time magazine story that I wrote about him in 2006 put it, "the scariest guy in Washington." The nickname that became the favorite of his highly regarded staff was "the mustache of justice."
I caught up recently with Waxman, who retired in 2015. What guidance, I asked, would he offer his old Democratic colleagues in the House, should they regain control of the chamber, and with it, subpoena power?
Given that Republicans have controlled the House for 21 of the past 25 years, this would be a learning experience for most of its Democrats. Only three of the 21 ranking Democrats in line to take over committees have ever run one as a chairman.
Waxman's advice might not sound very satisfying to those who see winning back the gavel as payback time, and a chance to make President Donald Trump's life miserable.
"Democrats have to be selective on what they're going to use their oversight and investigative powers to look at. They're going to have to be moderate in their approach, so that they don't look like they are partisan efforts and that they are using these tremendous powers in a legitimate way," Waxman said.
For starters, Waxman does not think much of the recent proposal by speaker-in-waiting Nancy Pelosi, D-Calif., to make obtaining Trump's tax returns one of the first orders of business for Democrats, as she told the San Francisco Chronicle's editorial board in an hour-long interview.
Before making such a move, Waxman said, Democrats must make a credible argument that they are embarking on more than a fishing expedition.
"If the Democrats say on day one, now we're going to do oversight and we insist on getting the president's tax records - that looks partisan, and it doesn't look legitimate," Waxman said. "If that's part of an investigation, they have to spell out what the investigation's about, what they're trying to accomplish."
A better focus, Waxman argued, would be using oversight power to delve into how Trump and the Republicans are governing: the regulations that are being overturned by executive fiat, as well as the officials who are running agencies whose very mission they oppose - some of whom are enriching themselves while they are at it.
"When they took the jobs in the Trump administration, they pledged to dismantle the agencies that they're controlling. So we ought to say, well, how's that going?" Waxman said. "These are very legitimate, focused investigations and oversight that will draw attention to the failure of people in this administration to enforce the laws that are on the books, which have very legitimate and essential purposes behind them."
There would be no small irony if Republican officials were to find themselves staring at the business end of subpoenas from a Democratic-controlled House. Their party created the potential for abuse in 2015, when the GOP majority vastly expanded the ability of committee chairmen to issue them unilaterally, without consulting the ranking member or the rest of the panel.
In the four years that Rep. Darrell Issa, R-Calif., sat in Waxman's old seat as chairman of the House Committee on Oversight and Government Reform during the Obama administration, he issued more than 100 subpoenas without debate or vote by the committee. By the Democrats' tally, that was more than the previous three chairmen combined.
Nor should we forget the Select Committee on Benghazi, whose chairman Trey Gowdy, R-S.C., issued 14 subpoenas unilaterally. Much of it was done with the intention of driving down Hillary Clinton's poll numbers, as House Majority Leader Kevin McCarthy, R-Calif., would later candidly admit.
That kind of behavior is not oversight; it is harassment. And it is dangerous. Unlike other kinds of subpoenas, those issued by Congress are not subject to judicial review. So there is no independent assessment of whether they are unreasonable, overly broad or onerous. The recipient has only two choices: comply or risk criminal prosecution for contempt.
Republicans have offered a model of how not to conduct legitimate congressional oversight. If voters decide to turn that power over to the Democrats, they should seize their opportunity to return this vital process to one that yields results the country will trust.
Karen Tumulty is a Washington Post columnist covering national politics. She joined The Post in 2010 from Time magazine and has also worked at the Los Angeles Times. @ktumulty